FTP stands for File Transfer Protocol. It allows you to upload, download, and edit files on a server. While Plesk has a very useful File Manager interface, often the easiest way to upload or download large numbers of files is to use FTP.
There are 2 main parts:
Creating an FTP User:
In your Rebel account, please go into your Hosting Manager and click Control Panel.
Below your domain click FTP Users
Here you will have a default FTP user. If you would like to use it, click on it and enter a password.
If you would like to create an additional user click Add An FTP Account.
Enter a username and password. This must be unique to the server (not just your account) so if you choose something common like "mike" it may already be taken. Here you can also choose which directory it has access to, for example if you would like to grant someone FTP access to only a specific directory.
How do I connect an FTP application?
Enter your credentials from the section above.
Username: The username you created above in Step 3.
Password: The password you created above in Step 3.
The right hand side of your window shows the server. Double click on the directory that contains your website (it's usually your domain name or httpdocs). You can then either drag and drop the files from your desktop into the right hand side of your Filezilla window, or navigate to your files on the left, and then drag them into your server on the right.